Metabolic Effects of L-carnitine on Type 2 Diabetes Mellitus: Systematic Review and Meta-analysis
received 26 November 2012
first decision 20 December 2012
accepted 10 January 2013
21 February 2013 (online)
Carnitine is an endogenous metabolite and exogenous nutrient with a pivotal role in lipid metabolism. Plasma levels of carnitine are reduced in type 2 Diabetes Mellitus (T2DM). The aim was to evaluate the metabolic effects of the administration of L-carnitine in T2DM.
A systematic review was performed. Relevant randomized, controlled-trials trials were searched in Pubmed, Trip Database and Cochrane Library, and selected when they had enough methodological quality assessed with the Jadad scale. Article search strategy included “Carnitine” OR “L-carnitine” AND “Diabetes Mellitus” OR “Diabetes mellitus, type 2” OR “Noninsulindependent-diabetes mellitus”. Meta-analysis was performed, and the difference of means calculated with a 95% confidence interval. Heterogeneity was evaluated with the Q statistic.
The systematic review included 4 trials with 284 patients. Oral L-carnitine lowered fasting plasma glucose [−14.3 mg/dl (CI95% − 23.2 to −5.4); p=0,002], total cholesterol [−7.8 mg/dL (95%CI −15.5 to −0.1); p=0.09], low density lipoprotein [−8.8 mg/dl (CI95% −12.2 to −8.5), p<0.0001], apolipoprotein-B100 [−7.6 mg/dl (CI95% −13.6 to −1.6); p=0.013] and apolipoprotein-A1 [−6.0 mg/dl (CI95% −10.5 a −1.5); p=0.523]. There was no significant heterogeneity. The changes in triglycerides, lipoprotein (a) or HbA1c were not significant.
The administration of L-carnitine in type 2 diabetes mellitus is associated with an improvement in glycaemia and plasma lipids.
- 1 Mingrone G. Carnitine in type 2 diabetes. Ann N Y Acad Sci 2004; 1033: 99-107
- 2 Mynatt RL. Carnitine and type 2 diabetes. Diabetes Metab Res Rev 2009; 25: S45-S49
- 3 Ferrannini E, Buzzigoli G, Bevilacqua S et al. Interaction of carnitine with insulin-stimulated glucose metabolism in humans. Am J Physiol 1988; 255: E946-E952
- 4 Stephens FB, Constantin-Teodosiu D, Greenhaff PL. New insights concerning the role of carnitine in the regulation of fuel metabolism in skeletal muscle. J Physiol 2007; 581: 431-444
- 5 Stephens FB, Constantin-Teodosiu D, Laithwaite D et al. An acute increase in skeletal muscle. J Clin Endocrinol Metab 2006; 91: 5013-5018
- 6 Mingrone G, Greco AV, Capristo E et al. L-carnitine improves glucose disposal in type 2 diabetic patients. J Am Coll Nutr 1999; 18: 77-82
- 7 Capaldo B, Napoli R, Di Bonito P et al. Carnitine improves peripheral glucose disposal in non-insulin-dependent diabetic patients. Diabetes Res Clin Pract 1991; 14: 191-195
- 8 Poorabbas A, Fallah F, Bagdadchi J et al. Determination of free L-carnitine levels in type II diabetic women with and without complications. Eur J Clin Nutr 2007; 61: 892-895
- 9 Ringseis R, Keller J, Eder K. Role of carnitine in the regulation of glucose homeostasis and insulin sensitivity: evidence from in vivo and in vitro studies with carnitine supplementation and carnitine defi ciency. J Nutr 2012; 51: 1-18
- 10 Derosa G, Cicero AF, Gaddi A et al. The effect of L-carnitine on plasma lipoprotein(a) levels in hypercholesterolemic patients with type 2 diabetes mellitus. Clin Ther 2003; 25: 1429-1439
- 11 Rahbar AR, Shakerhosseini R, Saadat N et al. Effect of L-carnitine on plasma glycemic and lipidemic profile in patients with type 2 diabetes mellitus. Eur J Clin Nutr 2005; 59: 592-596
- 12 Santo SS, Sergio N, Luigi DP et al. Effect of LPC on functional parameters and oxidative profile in type 2 diabetes-associated PAD. Diabetes Res Clin Pract 2006; 72: 231-237
- 13 Malaguarnera M, Vacante M, Avitabile T et al. L-carnitine supplementation reduces oxidiced LDL cholesterol in patients with diabetes. Am J Clin Nutr 2009; 89: 71-76
- 14 Ringseis R, Keller J, Eder J. Role of carnitine in the regulation of glucose homeostasis and insulin sensitivity: evidence from in vivo and in vitro studies. with carnitine supplementation and carnitine deficiency. Eur J Nutr 2012; 51: 1-18
- 15 Ceriello A, Quagliaro L, Piconi L et al. Effect of postprandial hypertriglyceridemia and hyperglycemia on circulating adhesion molecules and oxidative stress generation and the possible role of simvastatin treatment. Diabetes 2004; 53: 701-710
- 16 Cuerda C, Luengo LM, Valero MA et al. Antioxidantes y diabetes mellitus: revisión de la evidencia. Nutr Hosp 2011; 26: 68-78
- 17 Valero MA, Vidal A, Burgos R et al. Meta-analysis on the role of lycopene in type 2 diabetes mellitus. Nutr Hosp 2011; 26: 1236-1241